MHD Turbulence Simulation in a Cosmic Structure Context

TL;DR

This paper investigates how weak magnetic fields evolve in turbulent, highly ionized cosmic gas media, revealing their growth towards energy equipartition and a transition in field topology.

Contribution

It presents a simulation study showing the evolution of magnetic fields in cosmic turbulence, highlighting their growth and structural transition.

Findings

Magnetic fields grow towards equipartition with kinetic energy.

Field topology transitions from filamentary to ribbon-like structures.

Magnetic fields become laminated with vorticity structures.

Abstract

The gaseous media of galaxy clusters and cosmic filaments, which constitute most of the baryonic matter in the universe, is highly dynamic. It is also probably turbulent, although the turbulence properties are poorly known. The gas is highly rarefied, essentially fully ionized plasma. Observational evidence suggests intracluster media (ICMs) are magnetized at some level. There are several possible origins for ICM seed fields; the observed fields are likely the result of turbulence in the ICM. We are engaged in a simulation study designed to understand in this context how very weak initial magnetic fields evolve in driven turbulence. We find that the magnetic fields eventually evolve towards equipartition levels with the vortical, solenoidal kinetic energy in the turbulence. As they do so the topology of the field structures transition from filamentary forms into ribbon-like structures in which the field orientations are laminated with vorticity structures.